import java.lang.StringBuilder

fun main(args: Array<String>) {
    val n = readLine()!!.toInt()
    val c = readLine()!!.split(" ").map { it.toInt() }
    var ans = ""
    c.indices.reversed().forEach { idx ->
        c[idx].let { cnt ->
            if(cnt > 0) {
                (idx+1).toString()[0].let { num ->
                    ans += "".padStart(cnt, num)
                }
            }
        }
    }
    println(ans)
}